If you order it online just select your school and you should get the discount.
Im not sure how it works in the store but if you go in have your school id and a copy of your last semesters schedule just in case. Dont tell them that you graduated.
I'm in the same exact situation you are. I am graduating in May and plan on buying a new macbook pro sometime soon. Just trying to decide which one I want and seeing when the back to school promo may start.
Getting the EDU discount used to be a very strict protocol. Last year, some users on here noted that they were simply asked if they were in college and were eligible. Online is wide open.